Primary Citation of Related Structures:   1UBQ
PubMed Abstract: 
The crystal structure of human erythrocytic ubiquitin has been refined at 1.8 A resolution using a restrained least-squares procedure. The crystallographic R-factor for the final model is 0.176. Bond lengths and bond angles in the molecule have root-mean-square deviations from ideal values of 0 ...
The crystal structure of human erythrocytic ubiquitin has been refined at 1.8 A resolution using a restrained least-squares procedure. The crystallographic R-factor for the final model is 0.176. Bond lengths and bond angles in the molecule have root-mean-square deviations from ideal values of 0.016 A and 1.5 degrees, respectively. A total of 58 water molecules per molecule of ubiquitin are included in the final model. The last four residues in the molecule appear to have partial occupancy or large thermal motion. The overall structure of ubiquitin is extremely compact and tightly hydrogen-bonded; approximately 87% of the polypeptide chain is involved in hydrogen-bonded secondary structure. Prominent secondary structural features include three and one-half turns of alpha-helix, a short piece of 3(10)-helix, a mixed beta-sheet that contains five strands, and seven reverse turns. There is a marked hydrophobic core formed between the beta-sheet and alpha-helix. The molecule features a number of unusual secondary structural features, including a parallel G1 beta-bulge, two reverse Asx turns, and a symmetrical hydrogen-bonding region that involves the two helices and two of the reverse turns.
Related Citations: 
Comparison of the Three-Dimensional Structures of Human, Yeast, and Oat Ubiquitin Vijay-Kumar, S., Bugg, C.E., Wilkinson, K.D., Vierstra, R.D., Hatfield, P.M., Cook, W.J. (1987) J Biol Chem 262: 6396
Three-Dimensional Structure of Ubiquitin at 2.8 Angstroms Resolution Vijay-Kumar, S., Bugg, C.E., Wilkinson, K.D., Cook, W.J. (1985) Proc Natl Acad Sci U S A 82: 3582
Crystallization and Preliminary X-Ray Investigation of Ubiquitin, a Non-Histone Chromosomal Protein Cook, W.J., Suddath, F.L., Bugg, C.E., Goldstein, G. (1979) J Mol Biol 130: 353
Molecular Conservation of 74 Amino Acid Sequence of Ubiquitin between Cattle and Man Schlesinger, D.H., Goldstein, G. (1975) Nature 255: 423
Organizational Affiliation: 
Howard Hughes Medical Institute, Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9050, USA.